Piston



April 13 1926. 1,580,491 F. JARDINE ET AL PISTON Filed May 2, 1921 2 Sheets-Sheet l April 13 1926. 1,580,491

' F. JARDINE ET AL PISTON Filed May 2, 1921 2 Sheecs;Seet 2 Patented Apr. 13, 1926.

UNITED STATES PATENT OFFICE.

FRANK J'ARDJNEI AND FERDINAND JEHI, on CLEVELAND, OHIO, ASSIGNORS, ZBY

MESNE ASSIGNMENTS, T ALUMINUM MANUFACIUBS, INCORPQRAIED,

CLEVELAND, OHIO, A. CORPORATION OF DELAWARE.

PISTON.

Application 111811 May 2, 1921. Serial No. 466,371.

T0 aZZ wlzom z't 9ay concem:

Be it known thatwe, FRANK J ARDINE and F ERDINAND JEHLE, citizens of the United States, residing at Clevc]and, in the county of Cuyahoga, State of Ohio, have invented certain new and useful Improvements in Pistons, of Which the followingis a specifi- Cation, reference being had therein to the accompanying drawings. a

10 This invention relates to pistons for internal combustion 'engines and has for. its .principal object the provision of a piston having a yieldable skirt capable of conforming to the walls of an engme cy1inde'r at all Working temperatures.

Another object is to construct a piston rovided with means whereby the mechan- 1cal expansion of the skirt of the piston, due to thethermal expansion of the piston head, is mininized and may be accommodated in an engine cyiinder.

Another object is to provide a piston having a yieldble skirt portion capable of contacting thruout its circumferential length with the walls of a cy1inder at various piston temperatures.

Another object is to provide an aluminum alloy piston having a yieldable skirt capable of conforming, at all workin temperatures,

to the walls of a cylindr Whl0h is composed of material having a relatively small coefliaient of expansion, as 'compared with aluminum 'alloys.

Another object is to provide a iston for an internal combustion engine aving a yieldable portion varying in Wall thickness in the direction of its circumferentiai length.

Obher objects will,be pointed out hereinafter.

In the following specification, our invention is described in sufiicient detai} to enable others skilled in the art to pract1ce it, referene bein had in the' specification to the drawings W ich are attached to"and form a part thereof, in which: v

Fig. 1 is a side elevation of one form of piston, embodying our invention;-

Fig. 2 is a sectional view taken on line 2-2 of Fig. 1 in the directionindicated;

Fig. 3 is a bottom plan'view of Fig. 1;

Figs. 4, 5 and 6 are yiews similar respectiveiy t0 Figs. 1, 2 and 3 of a modified form of piston.

The form of piston illustrated in Figs. 1, 2 and 3 ,compr1ses apiston head 1, and a skirt 2attached'thereto. The skirt 2 Which is substantiall clindrical has two 0 positely dispose bearing walls 3, joine by tWo opposite walls 4:, the outside diametricai dimensions of all of which are substantially the same as the diameter of the engine cylinder in Which the piston is to remprocate. The walls 3 and 4: t-hus practicaliy engage with the cylinder walls when the piston and cjylinder are assembled. ,t

Attached to the head 1 on opposite sides thereof, are boss carrying walls 5 which are depressed inwardly or relived on the outer surface suificiently t0 provide ample clearance for all purposes between the walls and the Cylinder. to head 1 strengthened by a cross rib 6 Which also assists in supporting the bosses 7. Each Wa1l 5 is united to both of the bearing Walls 3 and together constitute the only con nection between wa1ls 3 and head 1.

The walls 5 are relieved or 'depressed Within the outer cylindrical contour et the skirt to a marked extent as is shown in Figs. 1 and 2, or even t0 a greater amount, and are separated from walls 4 by circumferen- Wa1ls 5 have their junction tia1 slots 8, or by openings cored out duringthe oil reservoir. A tapered or beveled upper edge 9 on each wall 4 assists in the removal of oil from the cylinder walls.

Each bearing wal1 3 is separated from head 1 by circumferentially extending slots, 10 and one wall has a slot 11 joining 51013 10 intermediate its ends and extending open end of the skirt, thus form1n two yldable portions 12. Slot 11 may j0m slot 10 at vanous other points, even at an end thereof in which Case only one yieldable Portion s formed. If desired, a similar slot 11 may be formed in each bearing wall. When assembled in an angine the pistons preferably (have the slot 11 located on the to the side of the piston 'which takes the least 4 diameters of the cylinder, the yieldable portiens 12 are capable of springing or bonding inwardly to compensate for the inoreased size of the piston and to permit its moving in the cylinder without scoring.

Preferably the portions 12 inerease in wall thickness in the direction of their length from their free ends to their point of support or junction with the skirt, which is indicated approximately by lime 1313 in Fig. 1. VVhen s0 formod, the inwardly directed force, applied by the cylinder walls on the portion, will be absorbed by the entire portion. The defiection or bending Will theref0re be distributed over the entire length of the portion and Will be substantially uniform in amount thruout the length thereof.

It will be evident that the resistance offered by the yieldable portion to any be1iding force can readily be increased or diminished by varying the thickness or lcngth of the portion. Likewise the wear on the yieldable portion which varies directly with the resistance'to dcflection, can be regulated by changes in wall thickness and length.

The modified form of piston shown in Figs. 4, 5 and 6 resembles the preferred form in many particulars. It consists of a head 21 and a substantially eylindrical skirt 22 of approximately the same enter diameter as the inside diameter of the cylinder and carrying the usual wrist pin bosses 23 which are supported in part froin the head 21 by webs 24:. These webs 24 may, if desired, be united by a connecting web as shown in Fig. 2. Adjacent the ends of each boss 23, the exterior cylindrical surface of the skirt is relieved several thousandths of a ineh over an area 25, substantially as in icated in Fig. 4. OH relief holes 26, leading inwardly from surfaces 25, permit escape of excess oil on the ylinder walls to the interior of the piston.

The bearing walls of the skirt are desi nated by 27 and 28. Wall 27 is preferaby separated from head 21 by a slot 29, although it may be made integral with the head, if desired. It extends with a continuous and unbroken surface to the open end of the skirt, while wall 28 is separated from the head by a similar, circumferentially extending slot 29 and extends lengthwise of the skirt to within a short distance of the end thereof where it is terminated by a circumferentially extending slot 30. A substantially vertical slot 31 joins the slots 29 and 30 intermediate their ends and forms two yieldable portions 32 capable of inward deflection or bending to compensate for expansion of the piston in excess of that of the cylinder. It is to be understood that the location of this slot 81 is not fixed but that it may join the slots 29 and 30 at various points (aven at their ends, thus forrnng only one yieldable portion.

Portions 32 prefcrably vary in thickness in the 7 direction of their circumferential length from a maximum at the point of support to a minimum at the free end to provide for a varying defiection of the portions as has been described in connection with the modification shown in Figs. 1, 2 and 3.

Between slot 30 and the open end of the skirt the outer surface of the latter is relieved circumferentially, the relieved surface 33 being eccentric with respect to the cylindrical surface of bearing wall 27. The maximum relief, amounting to several thousandths of an inch depending upon the size of the piston, thus lies immediately below the center line of bearing wall 28.

As the piston expands in excess of the expansion of the cylinder, the bearing walls 27 and 28 press more tightly against the cylinder walls, yieldable portions 32 bending inwardly to compensate for this excess expansion and to maintain the dianieter of the bearing walls substantially the same as that of the cylinder. The skir-t of the piston thereby automatically conforms to the cylinder unti] it has increased t0 sueh an extent that surface 33 contacts with the cylinder 'walls, when the yielding action of the portiens 32 is of practically no further advantage. Surface 33 is, however, relieved sufliciently to permit the calculated maximum expansion of the skirt before the surface can engage the c vlinder wall.

Provision has been made against the passage.of excess oil past the piston andinto the combustion chamber. Little oil can pass the bearing walls of the pistondue to the close fit in the cylinder. Between these bearing wall surfaces, the walls which comprise parts of the cylindrical surface of the skirt have relatively close engagement with the cylinder and thus prevent the passage of oil While the depressed surfaces adjacent the bosses and their relief openings afiord means of collecting and draining oil from the cylinder walls.

In each piston herein disclosed, the longitudinal slot is shown meeting the circumferential slot or slots intermediate their ends. It is to be understood, however, that substantially the same advantages could be obtained if the longitudinal slot should join the circumferential slots et or near one end thereof, thereby forming only one yieldable portion. The wall thickness of such portion may vary, as in the above described portions.

Altho only one piston metal has been mentioned specifically in this specification, it is to be understood that the invention is applicable to all suitable piston metals Or alloys having a coefficient of expansion greater than that of iron, for example, magnesium and its alloys. 7

Altho We have shown and described two modifications of our invention, we do net tails set forth since these m o ifications are intended to be merely illustrative.' Many changes, falling within the scope of our invention, Will doubtless occur to these skilled in the artafter a knowledge of these disclosures is obtained. We, therefore, desire that ourinvention be limited only to what is claimed.

What is claimed:

1. A piston for an internal combustion enqine comprising an integral head and skirt. cylinder engaging bearing wa]ls in the skirt, and a yieldable portion in one of the said bearing Walls Varying in Wall thickness in the direction of its circumferential length from a maximum at its point et support to 'a minimum at its free end.

2. A piston for an internal combustion cngme compr1s1ng a head and a sk1rt 1ntegral therew1th, wr1st p1n bosses 111 the slnrt,

the skirt having oppositely disposed bearing Walls extending from adjacent the head to the end of the skirt, one of the said walls comprising a yieldable portion having a substantially cylindric al exterior surface extending to below the bosses from adjacent the head, and a rlatively nonyieldable por tion having an exterior surface 'of shorter radius than the surface of the said yieldable portion. 7

3. A piston for an internal combustion engine having an integral head and skirt, the skirt comprising a continuous, unbrokeu bearing Wall, an oppositely disposed bearing wall provided with a circumferentially extending yieldable portion varying in wall thickness in the direction of its length and an annular wall oifset-inwardly with respect to the said yieldable portion.

4. A piston for an internal combustion angine comprising a head and a skirt, the skirt having a plurality of flexible circumferentially extending portions varying uniformly in wall thickness in the direction of their free ends.

5. A piston for 'an internal combustion cngine comprising a head and a. skirt inte- 'gral therewith, Wrist pin bosses in the skirt,

the skirt having oppositely disposed bearmg Walls extending from adjacent tlie head to the eI 1d of the skirt, one of the said Walls compr1smg a yieldable portion having a substantially cylindrical exterior surface extend1ng t0 below the bosses from adjacent the head and a relatively nonyieldable portxon separated from the yieldable portion by a c1rcumferential slot and havmg au cxter1or surface of shorter radius than the surface of the said yieldable portion.

6. A piston for an internal combustion engme comprising a head and a skirt integral therew1th, wrist pin bosses in the skirt, the sk1rt haVmg oppositely disposed bealing Walls extending from adjacent the head to the end of the skirt and provided with sub stant1ally cylindrical exterior surfaces, one of sa1d walls being composed of separate portions of substantially the saine insid d1ameters and diflerent outside diameters,

the portion of greater outside diameter be-- mg separated from the head and the portion of smaller outside diameter by circumferential 'slots, and having a longitudinal slot o ning the circumferential slots intermediate their ends.

In testimony whereof We affix our signatures. A

FRANK J ARDINE. FERDINAND J EHLE. 

